My jeep throttle body works but sucks d*ck

[earthwonder83]

I spent one full day on this. The idle is f*cken stupid. It hangs around 1300 to 1900 rpm. The butterfly plate also gets stuck and the car unpredictably wants to drive when trying to stop. I triple checked everything.

 

[Mike1992]

sounds like the throttle body needs a heavy cleaning. the plate shouldnt be sticking give it a very thorough cleaning and report back

This means take it off to clean it!

 

[top_end95]

Originally posted by earthwonder83
I spent one full day on this. The idle is f*cken stupid. It hangs around 1300 to 1900 rpm. The butterfly plate also gets stuck and the car unpredictably wants to drive when trying to stop. I triple checked everything.

Did you just get a Jeep TB and stuck it on there?

If you did, you need to do more research on it. The Jeep TB mod you see around these boards is a Hybrid of your stock 420a TB and the Jeep TB.

PM Doug99RS to find out what all is involved in this mod.

 

[talon94es]

Yep. I've read so many post from Doug99RS in regards to this since he used to Fab them. All and all, it appears to be much more trouble then it's worth! And dangerous to boot. Take that $hit off.

 

[earthwonder83]

I cleaned it must have about 3 times. Its cleaner than anything else in the engine compartment. I modified it exactly as the the 2gnt ariticle said so. The only thing that really bothers me is the high idle. I plugged the manifold hole tightly. I found a vaccuum source for the unused emmision line. I've narrowed it down to the butterfly. Whenever I push the butterfly manually to close it completely shut, the idle goes down. The problem is, if i set the idle screw too low, it gets stuck. When I do push in the butterly, I can get about 1000 rpm or less. I deburred the edges of the butterfly and will fire it up again.

 

[top_end95]

I couldn't find the write-up on 2gnt.com

You also didn't answer my quesiton. PM Doug99RS, he is the one who assembled that mod!

Or better yet....

 

[Doug99RS]

More than likely you've got one of two problems. Either the throttle plate itself is hitting the side of the throttle body housing or the black plastic piece is not cut right. I've done three or four of these with less than satisfactory success. Some of the problems I faced were the spring slipping between the plastic piece and the throttle body housing, the black plastic piece not being smooth, and the throttle shaft having too much side to side movement which allowed for the throttle plate to contact the side of the housing thus causing it to drag.

It doesn't sound like a dirty throttle body to me. The average gunk build up from crankcase fumes and dirt particles that get past the throttle body will cause the car to starve for air long before it actually binds the throttle plate.

Another thing you may want to do is take the idle air control motor back out and unscrew the tip of it about 1/4 turn. Then reinstall it. You may need to do this two or three times. BUT you need to first fix the sticking throttle plate condition before adjusting the iac motor because it may be in the correct position.
Doug

 

[earthwonder83]

The best position for the IAC tip in my opinion is closest to the throttle body itself, if the tip is too far away from it the idle is way too high. I did found out the problem though. Actually two problems that are related. The throttle plate(butterfly) was touching the throttle body. I took some high grit sandpaper is just barely made it smooth and I got any gunk buildup left that I missed around where the plate lies. Then the next problem is the throttle cable itself. Even when I did completely let the slack for the cable go, the throttle plate housing would not touch the idle screw, thus not allowing complete plate closure. I found out the cable was about 1 or 2mm too short. To solve this I took a dremel w/ a cutting blade and trimmed slightly the inner area of the hard black plastic which the cable lies on. Ths made the slack on the cable even less. Now, the throtte plate mechanism does touch and click on the idle set screw. Everything up to now has made the idle between 1100 and 1200 which is kinda acceptable. Sometimes I can get 1000 rpm. My question is, are these normal rpm numbers for a big throttle body? If I set my idle screw any lower the plate sticks, but the idle goes under 1000 rpm. I haven't had any problems with the spring sticking between the two structures yet...

 

[Doug99RS]

The throttle plate should be allowed to close even more. Target idle is around 700-800 RPM regardless of the throttle body. Your problem of it sticking, after screwing in the set screw more, is the same problem I was referring to.

One thing to keep in mind about the idle air control motor is that is moves in and out based on engine RPM. If idle is too low, the idle control motor unscrews or backs out the tip to allow more air to go in. Other way around if it's idling too high. Point here is that it's always moving and when the car is shut off or cranked up, you never know which position the idle motor is in (unless you engineered the thing). So screwing it as far out as possible may NOT necessarily be ideal. But again, you'll need to address the throttle plate position problem first before messing with the IAC motor.
Doug

 

[earthwonder83]

I was running the tb around for a while and got a check engine light. I'm guessing this is related to the wrong place where I tapped in the unused emmision hose. Well, I put it in the rubber capped area wher the IAT sensor lies. Is this right? When I take the hose off, I don't get a check engine light. Where is the ideal position for this hose. I thought about tapping a hole in my metal CAI. Is this a good idea? What if I just never cared about it, what affect will this have, if any?